Provided herein are methods and devices for printing of charge to a substrate surface, including by electrohydrodynamic jet (e-jet) printing, such as the e-jet systems and devices of PCT Pub. No. 2009/011709 (71-07WO). In particular, the performance and of e-jet systems for printing patterns of charge are improved by careful control of the process to avoid charge dissipation during the printing as well as after the charge is transferred to the substrate surface.
In conventional e-jet systems, effort is often directed to accurate and reliable liquid droplet placement of the printable fluid on the corresponding substrate surface. Accordingly, little or no attention is paid to printing of charge, and oftentimes the transfer of charge to the substrate is seen as undesirable in that charge build-up on the substrate can have undesirable effects on the printing of the fluid. Whereas previous systems have attempted to avoid or minimize the problem of charge transfer associated with e-jet printing, provided herein are methods to maximize charge transfer, including minimizing transfer of bulk fluid in which the charge is contained. The high resolution printing of charge processes provided herein are useful in a number of applications ranging from electronics, photovoltaics, document security and tracking, and in the biological or chemical sensing fields.